1. Field of the Invention
The present invention relates generally to magnetic heads for hard disk drives, and more particularly to magnetic heads having multiple layer write head induction coils, and methods for the fabrication thereof utilizing aspect ratio dependent etching such as the reactive ion etch (RIE) lag phenomena.
2. Description of the Prior Art
Magnetic heads commonly include write heads having two magnetic pole members and a flat, spiral induction coil disposed therebetween. Write head electrical current that passes through the induction coil creates a magnetic flux in the two magnetic pole members, and the magnetic flux passes through a write head pole tip, to write magnetic data bits onto the media, such as a hard disk, that is disposed proximate the pole tip. To improve the performance characteristics of write heads, efforts have been directed to increasing the magnetic flux that is generated by the induction coil in order to increase the magnetic field at the pole tip, such that data bits can more easily and reliably be written onto the magnetic media.
One prior art method for increasing the write head magnetic flux is to increase the number of induction coil turns that are fabricated between the two magnetic pole pieces. These efforts have lead to redevelopment of multiple layered induction coils. However, such multiple layer induction coils, as are known in the prior art, are generally difficult to reliably fabricate. Specifically, the prior art dual coil fabrication methods have generally employed well known photo-lithographic techniques which have resulted in problems related to the difficulty of removing the plating seed layer between coil turns, as well as a difficulty in filling the space between coil turns with alumina, or a similarly acceptable insulation material, following the plating of the coil turns. The present invention utilizes a selective plasma etching fabrication technique that takes advantage the aspect ratio dependent etching properties of the well known RIE lag phenomena, wherein etched structures having differing widths are etched to differing depths, to avoid the prior art problems.